HEFEI, Aug. 28 (Xinhua) -- Squatting on the riverbank with his students, Cui Hongbiao carefully observes rice growing in a floating field in the water, with the sweat on his forehead glistening in the August sun.
As a teacher at the School of Earth and Environment at Anhui University of Science and Technology (AUST), Cui was pleased to see the once lifeless coal-mining subsidence area transformed into a thriving
